Insulator



June 9, 1936. c. B. VAN ATTA INSULATOR Filed Nov. 26, 1926 Patented June 9, 1936 UNITED STATES PATENT OFFICE INSULATOR Application November 26, 1926, Serial No. 150,744

4 Claims.

The invention relates to insulators, particularly those of the suspension type used in connection with high tension lines.

The principal object of the invention, generally stated, is the provision of an insulator of that type embodying metallic connecting or suspension elements cemented upon or within a dielectric body, equipped or provided with means interposed between the dielectric body and the cement for the purpose of preventing adhesion of the cement to certain areas and permitting slight slippage or movement of the component parts of the insulator upon the application of strain or as the result of expansion and contraction under different thermal conditions.

It is well known that in insulators of this type it has been a practice to apply a coating of asphaltum or the like to the metal parts at all or a part of the areas thereof engaging the cement used for securing the cap and pin or other equivalent elements to the dielectric body, this coating acting to permit slight relative movement of the parts. However, it has been discovered that an insulator so treated in its assembly may in time lose a portion of its efiiciency .for the reason that material such as asphaltum may eventually become dry and brittle .so that it may crack or crumble. Clearly, when this condition occurs the beneficial results derived from the employment .of such yieldable material are lost or no longer exist.

Furthermore experiments have proved that unless slight slippage is permitted between the dielectric body and the masses of cement employed for securing the cap, or its equivalent and the pin, or other corresponding element internal strains in the dielectric body and the cement may be brought about during temperature changes owing to the different co-efiicients of expansion of the two materials. In addition to this, any tendencies of the cement .and dielectric material to expand or contract may result in a strain at the area of union.

It is with the above facts in View that 'I have designed the present invention which has for an important object the provision of an insulator of the cap and pin or other type in which there is provided a coating or lining of yieldable or ductile material between the dielectric body and the masses of cement employed for securing the cap and pin, or equivalent elements, in place.

A more specific object of the invention is to provide an insulator having a preferably metallic liner at those portions of the areas of the dielectricbody lying within the field of greatest mechanical strain, such liner acting not only to prevent adhesion of the cement at such areas and to permit slight slippage but also operating to compensate or allow for or to take up any differences in the thickness of the dielectric body at such areas or the thickness of the cement mass or masses consequent to any out-of-round condition of the dielectric body as might occur in accordance with unavoidable variations in manufacture, for instance distortion during firing.

Another important object of the invention is to provide an insulator having a stern and a recess, the former carrying a suspension cap or the like and the latter having anchored therein a pin or its equivalent, the stem, recess and head of the pin, as well as the cap all being of such shape or formation as to give the cement, employed for securing purposes, a locking action rather than utilizing it as an adhesive.

Still another object of the invention is the provision of an insulator of this or an equivalent type in which the coacting or opposed surfaces of the pin head, stem and cap bell are so related that a wedging action will be produced upon relative outward movement of the cap and pin, the force exerted by the cap and cement therein against the dielectric body being inward and balancing the outward force exerted by the pin head and mass of cement between it and the dielectric body, the outward and inward pressures against the stem being neutralized.

A further object of the invention is to provide an insulator in which the pressure transmitting areas or portions of the pin and cap and coacting surfaces of the dielectric body are, in addition to being inclined with respect to the axis of the insulator, and preferably parallel, located at progressively decreasing distances from the horizontal.

Another object of the invention is the provision of an insulator in which the cap has the inner edge of its open end projected inwardly beyond the inner periphery of the major portion of the cap to assist in the above referred to locking action, the inner surface of the inwardly directed edge portion of the .cap being preferably equipped with a liner, for instance of metal as set forth in my co-pending application filed May 4, 1926, Serial No. 106,662,, this liner performing the same function as those provided between the dielectric body and the masses of cement or equivalent material utilized for holding the cap and pin in place.

An additional object of the invention is to provide an insulator embodying the above mentioned characteristics and which will moreover be simple, easy to manufacture and assemble, positive in action, eflicient and durable in service, and a general improvement in the art.

To the attainment of the foregoing and other objects and advantages, the invention preferably consists in the detailed construction and the arrangement and combination of parts to be hereinafter more fully described and claimed, and illustrated in the accompanying drawing in which:

The figure is a vertical or longitudinal section taken through an insulator embodying the invention.

Referring more particularly to the drawing the numeral I designates, generally, an insulator constructed of suitable dielectric material, preferably porcelain, as is the usual practice and this insulator is here represented as comprising a body having an outstanding skirt portion 2 formed with any desired number of petticoat elements 3 for the purpose of increasing the current leakage path. This body is shown as formed with an upstanding stem 4 which has its intermediate portion 5 of inverted frusto-conical shape and merging into the cylindrical upper portion 6 and also merging into the constricted neck portion I at the juncture of the stem with the skirt portions. The exact inclination or taper of the frusto-conical portion may of course be varied within certain limits as will be understood. The stem 4 is provided with a recess 8 which has its intermediate portion 9 of inverted frusto-oonical shape with preferably the same taper as the corresponding exterior portion of the stem. The width of the tapered or frustoconical outer and inner portions of the stem may be and preferably is the same though it should be noted that the tapered portion of the recess wall is located higher than the corresponding portion of the exterior wall. The tapered portion of the wall of the recess merges into a cylindrical wall portion I and into the surface of the underside of the body.

The insulator further includes a cap I I here shown as of the clevis type though it will be obvious that another variety may be used depending upon choice. This cap is of preferably flaring shape throughout with an inwardly curved flange portion I2 at its lower or open end. The cap is intended to fit about the stem 4 and to be secured with respect thereto and the opening at the lower end of the cap while considerably less in diameter than the major portion of the cap must of course be of suflicient size to permit its being engaged over the stem.

It is preferable, though not essential, to provide a liner I3 within the curved flange portion I2 of the cap and this liner may be mounted in position in any desired manner as for instance in accordance with the disclosure in the above mentioned co-pending application. This liner preferably has its inner surface I4 inclined and parallel with the surfaces 5 and 9 of the stem.

The insulator also includes a pin I5 the detailed construction of which must of course correspond to that of the cap so that a plurality of the units may be connected in series as is a common practice. The pin terminates in an inverted frusto-conical head I6 located within the recess 8 in the cap, this head having a taper preferably corresponding to that of the walls 5 and 9 of the stem and the surface I4 of the cap liner I3 if such a liner is used. If such a liner is omitted, it is intended that the flange portion of the cap have an inclined surface corresponding to the surface I4 of the liner. The pin is secured within the recess 8 of the cap by a mass of cementitious of other equivalent material I! and the cap is similarly held upon the stem by cement or the like I8. Clearly this cement will cooperate with the inclined or tapered portions of the pin, stem and cap to lock them in position so that displacement after setting of the cement will be impossible. The tapered or undercut shape of the stem, recess and pin and the inward inclination or curve of the bell of the cap will insure a locking action which will preclude separation of the parts except by destruction of the insulator.

Obviously the surfaces 5 and 9 of the stem receive the inward and outward forces, respectively, exerted by the cap and pin when longitudinal strain is applied to the insulator tending to separate the cap and the pin as occurs in service. It is desirable, partly for this reason and partly to permit relative movement of the parts as the result of expansion and contraction under temperature variations, to permit slippage at these areas of strain. To accomplish this I provide linings or coatings I9 and against the surfaces 5 and 9 respectively and formed of yieldable or ductile material of such character that it will not change its nature under the influence of time. A relatively soft metal such as lead or certain alloys is highly desirable for the purpose as such material is capable of flowing under compressible and dragging strain so as not only to permit slight slippage and prevent adhesion of the cement to the porcelain but also to accommodate inequalities in the surfaces such as might result from any out-of-round condition of the stem at adjacent points. It is desirable that the liners, which may be separate metal elements or the like inserted in place or which may be made in the form of a coating fully cover the walls 5 and 9 of the stem and that they lie between the lines 2| and 22 which bound the strain areas and which are normal to the uppermost and lowermost edges of the tapered head of the pin, the tapered walls 5 and 9 and the inclined surface I4 of the liner I3 or of the bell of the cap as the case may be. It will be observed that these fields of strain are frusto-conical in shape and flared downwardly so that when the wedging action occurs in the use of the insulator the compressible and bursting strains upon the dielectric stem will be neutralized.

From the foregoing description and a study of the drawing it will be apparent that I have thus attained the desired objects and have produced an insulator which will efiiciently perform all the functions for which it is intended. It is really believed that the construction, operation and advantages will be readily understood by one skilled in the art without further explanation.

While I have shown and described the preferred embodiment of the invention and have illustrated it in connection with a suspension insulator of the pin and clevis type it should be distinctly understood that this is merely an exemplification of the principles and general structural characteristics involved as I reserve the right to make all such changes and modifications as will widen the field of utility and increase the adaptability of the device provided such variations constitute no departure from the spirit of the invention or the scope of the claims hereunto appended.

Having thus described the invention, I claim:

1. An insulator comprising a non-conducting shell, a pin, said shell having a recess therein receiving one end of the pin, which recess has a single, continuous, unidirectional strain receiving surface tapering inwardly towards the free end of the pin, cement filler within the recess and surrounding the pin to retain the pin in position within the shell, said shell having an outer single, continuous, unidirectional strain receiving surface tapering in the same direction as the strain receiving surface of the recess, a cap embracing said outer strain receiving surface, cement filler within the cap and surrounding said outer strain receiving surface to retain the cap and shell in proper relationship, and soft metal coatings separating the strain receiving surfaces from the fillers adjacent thereto.

2. An insulator comprising a non-conducting porcelain shell, a pin, said shell having a recess therein receiving one end of the pin, which recess has a single, continuous, unidirectional strain receiving surface tapering inwardly towards the free end of the pin, cement filler within the recess and surrounding the pin to retain the pin in position within the shell, said shell having an outer single, continuous, unidirectional strain receiving surface tapering in the same direction as the strain receiving surface of the recess, a cap embracing said outer strain receiving surface, cement filler within the cap and surrounding said outer strain receiving surface to retain the cap and shell in proper relationship, and a soft metal coating separating the strain receiving surface 01' the recess from the filler therein.

3. An insulator comprising a non-conducting porcelain shell, a pin, said shell having a recess therein receiving one end of said pin, the surface of said recess having a single, continuous, unidirectional strain receiving portion, cement filler within the recess and surrounding the pin to retain the pin in position within the shell, said shell having an outer surface having a single, continuous, unidirectional strain receiving portion, a cap embracing said outer surface, cement filler within the cap and surrounding said outer surface to retain the cap and shell in proper relationship, and a. soft metal coating separating the strain receiving portion of the outer surface from the filler within the cap and rendering it unbonded with the filler.

4. An insulator comprising a non-conducting shell, a pin, said shell having a recess therein receiving one end of the pin, which recess has a strain receiving surface tapering inwardly toward the free end of the pin, cement filler within the recess and surrounding the pin to retain the pin in position within the shell, said shell having an outer strain receiving surface tapering in the same direction as the strain receiving surface of the recess, a cap embracing said outer strain receiving surface, cement filler within the cap and surrounding said outer strain receiving surface to retain the cap and shell in proper relationship, and soft metal coatings separating the strain receiving surfaces from the fillers adjacent thereto.

CLOYD B. VAN A'II'A. 

